1. Field of the Invention
The present invention relates generally to the fields of histology and cytology, and in particular to a rapid method for preparing paraffinized cell blocks from both tissue and sputum specimens.
The preparation of paraffinized tissue sections for examination under a light microscope typically involves fixation of a tissue specimen, preparation of a paraffinized tissue block from the fixed tissue specimen, and slicing of the block into the thin tissue sections. Preparation of the tissue block is itself a time consuming, multi-step process requiring dehydration of the fixed specimen with alcohol, clearing of the alcohol with a suitable solvent, and impregnation of the specimen with a paraffin wax. Moreover, both the dehydration step and the clearing step require immersion of the specimen in a graded series of reagents for comparatively lengthy periods of time. The time required for tissue block preparation by conventional procedures is typically about 12 hours, or longer. Although the treatment times can be reduced by approximately one-third by employing vacuum-assisted immersion, the necessary treatment time is still 8 hours or longer.
Thus, it would be highly desirable to provide more rapid methods for the preparation of cell blocks from tissue specimens. It would be particularly desirable if such methods were also applicable to other cell preparation techniques, such as the preparation of cell blocks from sputum samples.
2. Description of the Relevant Art
The use of microwave energy to fix tissue specimens has been suggested. See, e.g., Login (1978) Am. J. Med. Technol. 44:435-437; Patterson and Bulard (1980) Stain Technol. 55:71-75; Hopwood et al. (1984) Histochem. J. 16:1171-1192; Hopwood et al. (1984) J. Pathol. 142:A5; Leong et al. (1985) J. Pathol. 146:313-321; and Login and Dvorak (1985) Am. J. Pathol. 120:230-243. None of these references teach the use of microwave energy in preparing paraffin cell blocks from fixed tissue specimens.